However, most of the expensive social services received by illegal immigrants are services that, by federal law, must be given to them or to their American-born children, who are by law American citizens.

The idea behind Proposition 200 is that people voting, registering to vote or applying for "public benefits" would have to prove their U.S. citizenship in Arizona.

Which, experts agree, probably would do little more than drive up the price for the fraudulent documents that most illegal immigrants already have.

What's more, "public benefit" is not defined further. The vagueness of that term most likely would spawn lawsuits and court challenges.

Also troubling: Government workers could be fined, jailed or sued if they failed to report suspected illegal immigrants. Workers at all levels of government would need to be trained in complicated immigration law so they can avoid prosecution and become, essentially, immigration police.

State officials estimate it would cost at least $27 million to implement Pearce's ideas.

"It's just a mess," says Alfredo Gutierrez, a longtime state Democratic party leader and one of the leading voices against the new law.

Again, though, the ins and outs of the proposition aren't the real issue. Pearce says the proposition's biggest job is to send the message that Arizonans (perhaps representing the American public) adamantly want illegal immigration addressed forcefully at all levels of government. They want something done to slow down those four million illegal immigrants estimated to be crossing the southern U.S. border each year.

The problem, as has been true throughout history, is that the issue of immigration isn't as black and white as politicians make it. Especially in Arizona.

Some background: Arizona used to be part of Mexico. In 1848, the United States won the Mexican-American War and, with that, the chance to buy Arizona and the rest of the desert Southwest from Mexico for $15 million. The Gadsden Purchase added the rest of present-day Arizona five years later.

In the 1850s and 1860s, Southern Democrats, a smaller number of Lincoln Republicans, and a few other groups began running out to the area to fight for control of the political future of the state. Mixed in with their politics and faiths was a desire to become prosperous. Also, they came out with a lot of other people who just wanted to be prosperous.

They bought up land and mining claims and built businesses next to Mexicans, who were doing the same thing based on the same desires and goals.

Some of these capitalists did well and hired more and more rural working-class Mexicans.

Then the copper and silver mines grew, sometimes out of old Spanish mines, and farms grew, sometimes out of old Hohokam Indian fields. Then water came. Then the military bases came. Then air conditioning came. Then good roads came, and then better cars came. Then hotels came. Then golf got big. Then California got more expensive. Then the Valley of the Sun began receiving more new residents than any metropolis in the country.

All this created a unique economy based heavily on labor-intensive work in the killer Arizona sun. For a profit to be made, workers doing that work had to come cheap. Mines, ranches, cotton farms, hotels, restaurants, golf courses and housing construction all flounder if the difficult front-line labor positions get too expensive to fill.

And all through this, the economy of Mexico continued to flounder, so people came north to prosper.

But that antebellum Southern mindset from Arizona's territorial days seems to linger:

"Cheap seasonal labor -- yes. Live among us -- no," says author and ASU historian Jack August. "Thus, [Prop 200] is not a departure from the exclusionist social and political culture of 19th-century Arizona."

Then, in 1993, Silvestre Reyes, chief of the Border Patrol at El Paso, Texas, implemented a two-week test project called "Operation Blockade." Four hundred Border Patrol agents were deployed around the clock in full view along a central 20-mile segment of the border separating the El Paso area and Juárez.

The project so dramatically reduced illegals crossing into El Paso that it became a permanent policy. And Reyes became a congressman.

The same policy was used in San Diego. Success again.

The problem was that, viewed holistically, the plan actually did little to curb illegal crossings. It just forced immigrants who had crossed near San Diego to cross farther east, and those crossing at El Paso to cross farther west.

A new El Paso del Norte formed between El Paso and San Diego in the late 1990s. With blockades and decreased interior enforcement, the best path from Mexico into the United States became a long walk through the Sonoran Desert toward Phoenix, where immigrants could find transportation to wherever they might find work.